The invention relates to a device for producing a homogeneous powder-air mixture, the device comprising a pressure section and a suction section, wherein the two sections merge in an outlet. The invention also relates to a method for generating a homogeneous powder-air mixture.
Devices for mixing powder and air are conventionally known. Powder-air mixtures of this type are required i.a. in the printing industry for dusting freshly printed sheets. DE 199 37 557 A1 discloses a device of this type, wherein powder and air are mixed. The powder-air mixture generated by this device is, however, not sufficiently homogeneous.
Other devices have been proposed for producing a more homogeneous mixture. EP 0 636 405 A2 e.g. discloses a device for mixing a solid matter jet with gas, which attempts to generate a homogeneous mixture of solid matter and air using a coaxially disposed lance. Such devices are very expensive to construct and their operation is susceptible to disturbances.
The thesis “Untersuchungen zum Einfluss der Gutaufgabevorrichtung auf die Strömungsmechanik in Fallrohrreaktoren” (Investigations of the Influence of the Material Feeding Device on the Flow Mechanics in Downpipe Reactors) from the technical faculty of the University Erlangen-Nürnberg, Thilo Schiebe, 1997, pages 104 and 105 describes a device into which primary air, fluidizing air, dividing air, and solid matter are fed and mixed within the device, the mixture being discharged in a downpipe. This structure is also expensive, with the fluidizing air being required to whirl the solid matter in a fluidized bed and mix it with the dividing air.
The published series from VDI publishers “Experimentelle und theoretische Untersuchungen zur Berechnung der Kennlinien von gasbetriebenen Einphaseninjektoren und Gutaufgabeinjektoren” (Experimental and Theoretical Studies for Calculating the Characteristic Curves of Gas-operated Single-phase Injectors and Material Feed Injectors) Düsseldorf, 1993, pages 48 and 49, 70 and 71 describes a single-phase injector in which two gases are mixed. The driving jet mass flow is divided into four partial flows and supplied to the injector. Devices of this type are not suitable for industrial use due to their complicated structure and insufficient reliability.
It is therefore the underlying purpose of the invention to provide a device for generating a homogeneous powder-air mixture that has a simple construction and guarantees the production of a homogeneous mixture.